I haven't lost Nathan! [ And there it was, the denial. It's clear Peter hasn't accepted the fact that Nathan's gone and that no matter what he does, he's not going to be able to save his brother. ]

So don't tell me that I can't fix this when you're the problem. [ He's angry enough to consider going back in time to get rid of Sylar entirely, but even he knows it's not what he would do or what Nathan would want him to do. He's not the villain of this story. ]

And do me a favor, okay? Don't talk about him like he's dead. [ His brother's alive and well back home in New York and whenever he gets to leave Wonderland, he's going to see him again. ] And don't tell me you understand because you don't. I don't need your sympathy.